A coupler for coaxial conductors and especially an antenna coupler is described in German patent document DE 196 09 571. In general, this coupler has an outer sleeve which can be cast or machined from metal and is formed with a massive sleeve. It may be made by turning and/or milling and has with its outer side a bulge which can be engaged by a locking element which can fix a plug, receivable in the coupler, and lock them together. The turning or milling of a solid material, like that on which the outer sleeve has been fabricated in the past is expensive and time-consuming.